1. Field of the Invention
An intake manifold for use with a downdraft carburetor of a motorcycle engine having a plurality of cylinders.
2. Description of the Prior Art
Often multi-cylinder internal combustion engines have a plurality of separate carburetors for each cylinder which require extensive maintenance. On the other hand, such engines may use a single manifold for fuel/air distribution to the individual cylinders. However, there remains a need for an efficient intake manifold for motorcycle engines.
U.S. Pat. No. 5,850,813 teaches a substantially Y shaped split intake manifold having fuel-air outlet conduits coupled to a plurality of internal combustion engine cylinder inlet ports.
U.S. Pat. No. 5,809,960 shows an intake pipe for an internal combustion engine to prevent the transfer of the vibrations to a carburetor. The intake pipe includes an intake pipe body connected to an outlet portion of a carburetor. The intake pipe body and two-intake pipe mounting flanges are formed as integral members.
U.S. Pat. No. 5,494,011 discloses an intake manifold for a combustion engine. Having a body with a front end, a back end, a top and a bottom. The bottom has a first angled portion; a second angled portion and a horizontal portion located therebetween. The intake manifold fur has a front end plate and a back end plate connected to respective ends of the body. The top plate has at least one opening for connecting at least one carburetor system to the intake manifold. The intake manifold further has a first and second engine mounting plate and a plurality of straight tubes each having a first and a second end. The straight tubes are connected at their first end to the body of the intake manifold and at their second end to the engine mounting plates.
U.S. Pat. No. 5,042,435 describes an intake manifold for twin carburetors or twin air control throat bodies for a motorcycle having one or more cylinders where the physical space is limited comprising a hollow central plenum chamber and hollow carburetor or air control throat body mounting flanges on each side adjacent. At least one side communicating with the intake track of at least one cylinder. In the case of two opposing cylinders, each cylinder communicates with the hollow central plenum chamber through opposing openings and the perpendicularly mounted carburetors or air control bodies. When a cylinder intakes a fuel mixture from the carburetors the fuel mixture from each carburetor converge in the hollow plenum chamber where the direction of flow is turned toward the cylinder without physical impact with a physical structure during direction change.
U.S. Pat. No. 4,934,342 relates to an intake manifold with left and right intake passages located respectively in left and right cylinder banks of an internal combustion vee-engine. The intake manifold comprises a single inlet passage portion, and two branch passage portions which branch from an outlet end of the inlet passage portion and which communicate respectively with the intake passages.
U.S. Pat. No. 4,872,424 shows an intake manifold. for use with a combustion engine having a lower manifold unit with lower runner portions and a lower plenum portion and upper manifold unit with an intake manifold opening surrounded by a carburetor mounting flanges, upper runner portions and upper plenum. When the upper and lower manifold units are assembled, the upper and lower plenum portions form a plenum chamber in fluid communication with the intake opening and the upper and lower runner portions forms plurality of intake runners between the plenum chamber and the respective cylinders each of which has an outlet port and a surrounding passageway side wall. The unit is constructed so that each outlet port is aligned in fluid communication with a respective cylinder intake port. Baffle means are removably mounted as part of the assembled unit for directing flow of the fuel mixture and form a relatively uninterrupted extension of each of the respective flow passageways.
U.S. Pat. No. 4,381,738 with adjacent expansible chambers of an engine provided with an intake runner set at least three runner passages conducting the working fluid from a common plenum to the expansible chambers, with at least one of the runners only serving one of the expansible chambers, at least another of the runners serving only the other expansible chamber, and at least still another of the runners commonly serving both of the expansible chambers.
U.S. Pat. No. 4,013,049 relates to an intake manifold having a plurality of upwardly extending headers connected to a single distribution manifold for use with a downdraft carburetor on a multi-cylinder motorcycle.
U.S. Pat. No. 3,247,834 describes a manifold structure comprising a housing, a chamber, a plurality of inlet ports provided in the housing in communication with the chamber for directing a fuel-air mixture thereto, baffle means in the housing and extending into a portion of chamber and being interposed between the single ports of associated pairs of inlet ports for separating the initial incoming flow of the fuel-air mixture, a plurality of spaced outlet ports provided in the housing and in communication with the chamber for exhausting the fuel-air mixture therefrom, the inlet ports and outlet ports in common communication with the chamber whereby each outlet port is provided with a uniform mixture and volume thereof for discharge from the chamber.
U.S. Pat. No. 2,013,737 discloses a manifold for gas engines having an intake, a distributing zone in communication with intake and four branches extending from the zone. Each branch has an independent discharge end spaced substantially apart from the other ends, the four branches being disposed so that a pair occupies in part a substantially parallel relationship with the pairs extending in relatively opposite directions from the distributing zone, one branch being relatively short as compared to the other branch of the same pair to secure said spacing of the discharge ends, and the inside corner of each branch where it communicates with its discharge end being such as to effect an abrupt turn, the formation of each branch adjoining its discharge and being formed to constitute recessed portions beyond the discharge end presenting with the latter abrupt corners.
FR 2384-120 teaches an engine with a suction manifold with six cylinder connections. The branches leave the manifold in pairs. The two branches of each pair being opposite each other on the manifold. Each branch has a straight section leaving the manifold and passing into a curved section leading to the cylinder inlet.